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Approval Letter Issued for Ziconotide
a Novel Painkiller
by Rosemarie Foster, BA, MA
Indication: Treatment of chronic intractable pain
Company Name: Elan Corporation, plc
Availability: Approval letter issued by FDA on 6/28/2000
Introduction
A novel painkiller isolated from the venom of an oceanic snail may soon be approved for marketing to help the hundreds of thousands of people with chronic pain that does not respond to conventional treatments. Called ziconotide (SNX-111), the drug is manufactured by Elan Corporation, plc, which received an approval letter from the FDA on June 28, 2000.
Ziconotide is a manmade version of a substance isolated from the venom of cone snails -- carnivorous oceanic snails that sting their prey with a cocktail of nerve-damaging chemicals injected through a harpoon-like tube.
Ziconotide is 100 to 1,000 times more potent than morphine; indeed, the cone snail venom (conotoxin) is potent enough to completely paralyze a fish within a matter of seconds. Scientists have harnessed this creation of nature to produce a new highly targeted painkiller that blocks critical openings in nerve cells, interrupting pain signals on their journey through the spinal cord to the brain. Ziconotide is administered through a small tube directly into the spinal cord.
How Does It Work?
Pain signals depend on the transport of calcium within cells. Ziconotide blocks the pain-associated channels through which calcium ions travel without interfering with channels that convey normal sensations. As a result, pain is relieved without causing numbness.
Clinical Study Results
Elan reported that the basis of the FDA approval letter were positive results from unpublished phase III clinical trial data on the use of Ziconotide in more than 700 patients with untreatable pain. The patients studied had either failed therapy with narcotics or could no longer tolerate therapy because of side effects. Significant pain relief was achieved in 57% of these patients. (ref. 2)
Brose and colleagues (ref. 3) described the use of ziconotide in a 43-year-old man who had suffered from chronic pain for 23 years after damage to the brachial plexus -- a network of nerves in the neck and shoulder. The patient reported complete relief of his pain.
Adverse Events
Adverse side effects reported by patients receiving ziconotide included dizziness, blurred vision, and jittery eye movement -- effects that could be resolved by reducing the dosage. Some patients experienced a slight reduction in blood pressure. Patients did not show signs of tolerance or
addiction, even after many months of treatment.
References
"Elan announces receipt of FDA approval letter for ziconotide." Press release, Elan Corporation, plc, June 28, 2000.
"Elan submits NDA for ziconotide." Press release, Elan Corporation, plc, December 31, 1999.
Brose, WG, et al. "Use of intrathecal SNX-111, a novel, N-type, voltage-sensitive, calcium channel blocker, in the management of intractable brachial plexus avulsion pain." Clinical J Pain 1997;13:256-259
Gibbs, WW. "A New Way to Spell Relief: V-e-n-o-m."
Scientific American, February 1996, pages 28-29.
Arnst, C, et al. "Conquering Pain." Business Week, March 1, 1999 issue..
Manufacturer Elan Corporation, plc
Treatment Class Analgesic and Anesthetic Antiinflammatory, Indication Treatment of chronic intractable pain (not approved by FDA as of July 2000)
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